release(v10.0.0)!: /brief defaults to chain=off (autonomous build is opt-in)

[aimsise]

TL;DR

Breaking (v10.0.0): /brief no longer auto-builds by default. A bare /brief <idea> now defaults to chain=off — it writes the brief (plus its autopilot-policy.yaml rescue file) and stops with manual next-steps, instead of chaining straight through /create-ticket → /autopilot to commits and PRs (and, since v9.0.0, spawning N wave-parallel ticket-executor worktrees). The autonomous build pipeline is now an explicit opt-in: pass chain=on.

Rationale: an argument-less /brief reads as "write a brief," but it triggered an implicit, hard-to-reverse, outward-facing pipeline — a poor default, and v9.0.0 widened its blast radius (N× concurrent worktrees + token spend). Making the gateway decision opt-in (while keeping full power — uc/parallel still default on — once you opt in) is the safer, least-surprise default.

Migration

# restore the prior idea-to-PR behavior:
/brief <idea> chain=on

Everything downstream of an explicit chain=on is byte-identical to v9.0.x (same /create-ticket → /autopilot handoff, same chained uc=on / parallel=on defaults). The mode=auto|manual legacy alias is retained and unchanged (mode=auto ≡ chain=on); only the both-keys-omitted default flips. Read-time resolution of pre-v6.0.0 key-less briefs stays chain=on (auto), deliberately asymmetric with the new write-time default.

What changed (8 files)

File	Change
skills/brief/SKILL.md	Flip the both-keys-omitted default to chain=off (Argument Parsing, mode-independence guard, frontmatter derivation, Finalization Step 2 gating). Every mode= alias literal + uc/parallel resolution preserved. Bare invocation deterministically takes the Step 3 manual path (no auto-kick.yaml, next_recommended_auto: "").
README.md	Opening pitch, argument signature, ultracode/wave-parallel default notes, mode table, execution-chains block, hero-diagram caption → chain=off default + chain=on opt-in.
docs/gen-brief-chain-flow.py + regenerated brief-chain-flow{,-dark}.png	Entry box relabeled /brief "<idea>" chain=on (opt-in).
tests/test-skill-contracts.sh	+CT-MODE-18 pins the chain=off default and drift-guards (negative clause) against the pre-v10.0.0 chain=on default returning.
CHANGELOG.md / .claude-plugin/plugin.json	## [10.0.0] — 2026-06-28 (BREAKING CHANGES + migration + Verification) / "version": "10.0.0".

Intentionally unchanged: create-ticket (its manual-brief next_recommended_auto lands on the existing v8.4.2 graceful, non-looping hard-stop); the mode= alias (its removal is a separate breaking change, deferred).

Verification

• tests/test-skill-contracts.sh: 915 / 915 (+1 = CT-MODE-18; CT-MODE-1..9 mode=-alias tests and CT-PARALLEL-1/7 stay green).
• tests/test-brief-lightening.sh 12/12 · tests/test-path-consistency.sh 145/145 · tests/run-all.sh ALL PASSED · shellcheck --severity=warning clean · CT-DECONTAM-1 clean · ac-evaluator twin byte-identity preserved (no agent edits).
• Reviewed via an adversarial multi-agent pass (residual-claim sweep · brief-consistency · CT-integrity/test-the-test · Stop-hook loop analysis · release-governance/PII) — verdict: clean, 0 confirmed findings.

See CHANGELOG.md ## [10.0.0].

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https://claude.ai/code/session_01Mw2bH4wbEPeebXsvSG6rWe